ADVANCED INSTRUMENTAL METHODS I — DU B.Sc. (Prog.) Applied Physical Science with Analytical Methods in Chemistry & Biochemistry Previous Year Question Papers

6 5.0(singlet, 2H) and 6 7.2 (singlet, 5H), IR bands intense at 740 cm-t. (4,5,6) 7. (a) Describe the various fragmentation mod?s for the benzophenone whose peaks in the mass spectrum appear at in/z 120, 105, 91 and 77. (b) Explaiii the pi.incipal and application of ]H-NMR and t3C-NMR spectroscopy in structure elucidation. (6) Explain the quantitative NMR (qNMR). What are the principles of qNMR? (4,5,6) 8. (a) Discuss the role of 2D-NMR in identifying molecular structure. (b) What are the terms magic angle s'pinning (MAS) and cross-polarization (CP-MAS) in solid-state (c) Discuss the factors affecting accuracy in qNMR measurements (relaxation time, pulse angle, acquisition time). 1. (a)Define the terms El and API of mass spectrometry. (b)Discuss the quadrupole and ESI in mass spectrometry. 2. (c) Explain the terms isotopic mass peaks & doubly/ multiply charged ions in mass spectrometry. (a) What are the .natural abundance, resolution and multiplicity of t3C NMR and [H NMR in decoupling spectroscopy? (b) Explain the ortho effect and nitrogen rule in mass spectrometry. (c) Explain to analyze fragmentation and base peak of n-butylamine and acetophenone to loss of CH3 and formation of benzoyl ion (in/z = 105). 3. (a) Explain the working alid importance ofNOESY & (b) How can do distinguish between 3-methyl cyclohexene and 4-methyl cyclohexene on the basis of mass spectroscopy? (c) Do the following nuclei have zero/non-zero magnetic moment? (Give reasons) 4. Write short notes on ANY THREE (5,5,5) (a) FT-ICR (Fourier` Transform Ion Cyclotron (b) Matrix-Assisted Laser Desorption Ionization (c) Fast Atom Bombarament (FAB) (d) Solid-stat6 NMR spectroscopy 5. (a) What are general fragmentation rules of mass spectrometry? (b) Explain the MCLafferty rearrangement of 2-pentanone and 1-pentene. Draw the transition state of both molecules. (c) What is the difference of noise decoupling and broad band decoupling? (3,6,6) 6.. (a) What is diastereotopicity? How does it affect NMR spectra. (b) Discuss the exchange spectroscopy (ESXY) and magic angle spinning (MAS). (c) Determine the structure of an organic compound of molecular formula C9H]o02 sliowed three peaks in the H NMR as given 6 1.96 (singlet, 3H),